[Update pending] The All Under Heaven expansion is confirmed to include Japan among others. Will update this review as soon as screenshots showing Japanese figure names in the game have appeared.

This game properly used the surname-firstname order for figures in feudal-era Japan (eg. Takeda Nobumitsu)

Early screenshots suggest that Japanese figures before the Meiji period will be named in the proper surname-firstname order (eg. Ouchi Hiroyuki, Kasai Sadakiyo)

This game properly used the surname-firstname order for historical Warring States-era figures (eg. Oda Nobunaga)

This remaster still uses firstname-surname order for Japanese historical figures in the Warring States era (eg. Jubei Yagyu instead of Yagyu Jubei)

Japanese historical figures from the Warring States era appearing in this game are named in firstname-surname order (eg. Tadakatsu Honda instead of Honda Tadakatsu)

Unlike prior series titles, this game looks set to have historical figures in Edo-era Japan named with proper surname-firstname order (eg. Miyamoto Musashi)

[Possible update] The Japanese representative leader in this game only has a single name (Himiko) and the Japanese civ featured at launch is from the Meiji era. Will update on future content releases.

This game properly used the surname-firstname order for Japanese historical figures prior to the Meiji era (eg. Minamoto no Yoritomo, Oda Nobunaga)

This game does properly use surname-firstname order for historical Warring States era figures (eg. Oda Nobunaga, Fujibayashi Nagato), but it is not well-received in Japan for other reasons.